1. Field of the Invention
The invention relates to a high-power radiation source having a discharge space filled with a filling gas which forms excimers under discharge conditions. One wall of which is formed by a first dielectric the discharge space is provided with a first electrode on its surface facing away from the discharge space. At least the first electrode and/or the first dielectric is transparent to radiation. An alternating power source is connected to the first and second electrodes to feed the discharge.
2. Discussion of Background
In this connection, the invention relates to a prior art, such as emerges, for example, from the lecture by U. Kogelschatz entitled "Neue UV- und VUV-Excimerstrahler" ("New UV and VUV Excimer Radiation Sources") delivered at the tenth Lecture Conference of the Gesellschaft Deutscher Chemiker, specialist group for photochemistry, in Wurzburg on Nov. 18-20 1987.
The V high-power radiation source presented at that lecture conference is described in detail as the technological background and prior art in the European Patent Application No. 87,109,674.9 of 6.7.1.87, the Swiss Application No. 2924/86-8 of 22.7.1986, and the U.S. Application No. 07/076,926 of 22.7.1987. That high-power radiation source can be operated with high electrical power densities and high efficiency. Its geometry can be matched within wide limits to the process in which it is used. Thus, in addition to large-area, flat radiation sources, cylindrical radiation sources which radiate inwards or outwards are also possible. The discharges can be operated at high pressure (0.1-10 bar). With this construction, electrical power densities of 1-50 kW/m.sup.2 can be achieved. Since the electron energy in the discharge can be optimized to a large extent, the efficiency of such radiation sources is very high, even if resonance lines of suitable atoms are excited. The wavelength of the radiation can be adjusted by the type of filling gas for example, mercury (185 nm, 254 nm), nitrogen (337-415 nm, selenium (196, 204, 206 nm), arsenic (189,.193 nm), iodine (183 nm), xenon (119, 130, 147 nm), and krypton (142 nm). As in the case of other gas discharges, mixing various types of gas is also recommended.
The advantage of these radiation sources is the two-dimensional emission of high radiation powers with high efficiency. Almost the entire radiation is concentrated on one or a few wavelength ranges. In all cases it is important that the radiation can emerge through one of the electrodes. This problem can be solved with transparent, electrically conducting coatings or, alternatively, also by using a fine-mesh wire gauze or deposited conductor tracks as electrode, which, on the one hand, ensure the supply of current to the dielectric but which, on the other hand, are largely transparent to the radiation. It is also possible to use a transparent electrolyte, for example H.sub.2 O, as a further electrode. This is advantageous, in particular, for the irradiation of water/waste water since, in this way, the radiation produced is fed directly into the liquid to be irradiated and the liquid serves at the same time as coolant.